Men who have sex with men (MSM) represent the largest proportion of AIDS deaths, and HIV incidence in the US. While prevention efforts targeting MSM have successfully reduced HIV incidence in the US, many men are not reached by these efforts, including male couples. Studies of gay men in Europe and the US report as high as 68% of new HIV infections being attributed to unprotected anal intercourse (UAI) within primary partnerships. As we enter into the final year of the Longitudinal Gay Couple's study it is clear that in order to develop an effective HIV prevention intervention for couples, we must further examine the three key areas: poorly-defined or broken agreements regarding sex outside the relationship, high rates unprotected anal intercourse (UAI) with primary partners and a lower level of HIV testing. For instance, our on-going study found that 32% of couples broke their agreement at least once in the past year yet less than half disclosed it to their partner. Additional specificity is needed to understand how broken agreements are linked with HIV risk. These broken agreements are often left undisclosed. Our work has also shown that discordant couples report UAI with their primary partner (47%). Our data suggest that agreements about sex with outside partners are distinct from agreements or discussions about sex within primary partnerships. Given the high rates of seroconversions occurring in gay male couples, within couple sexual agreements, relationship factors associated these agreements, and risk should be explored. While the on-going LCS examined agreements about sex with outside partners, the proposed study will additionally examine the characteristics of agreements within the relationship. Moreover, our data showed a substantial proportion of HIV-negative men engaged in UAI with a discordant or HIV status unknown partner in the 90 days, yet they had not tested for six months or more. The disturbing patterns of a lack of testing, broken agreements, and non-disclosure, and UAI among discordant couples must be examined in further detail so that we can develop an intervention that is effective and relevant to couples at risk. We propose to continue our program of mixed methods research examining HIV risk in the context of gay male couples. We will recruit and qualitatively interview 20 new couples within the first six months of the study to examine relationship factors associated with HIV testing and develop a new measure of HIV risk perception and attitudes towards HIV testing that is specifically developed for gay couples. Meanwhile, we will continue to follow the cohort of couples participating in the on-going LCS (we estimate that approximately N=100 will be retained) and recruit a supplemental sample of 400 new couples to examine new and more specific quantitative lines of inquiry regarding agreements and couple-based motivations for HIV testing as well as to provide enhanced statistical power to increase our ability to detect associations between variables of interest in the original study. Finally, we will begin development of a couples-based intervention for gay couples using focus group and qualitative interview methods (N = 52).